README
¶
ants
A goroutine pool for Go
Library ants implements a goroutine pool with fixed capacity, managing and recycling a massive number of goroutines, allowing developers to limit the number of goroutines in your concurrent programs.
Features:
- Automatically managing and recycling a massive number of goroutines.
- Periodically purging overdue goroutines.
- Friendly interfaces: submitting tasks, getting the number of running goroutines, tuning capacity of pool dynamically, closing pool.
- Handle panic gracefully to prevent programs from crash.
- Efficient in memory usage and it even achieves higher performance than unlimited goroutines in golang.
Tested in the following Golang versions:
- 1.8.x
- 1.9.x
- 1.10.x
- 1.11.x
- 1.12.x
How to install
go get -u github.com/panjf2000/ants
Or, using glide:
glide get github.com/panjf2000/ants
How to use
Just take a imagination that your program starts a massive number of goroutines, from which a vast amount of memory will be consumed. To mitigate that kind of situation, all you need to do is to import ants package and submit all your tasks to a default pool with fixed capacity, activated when package ants is imported:
package main
import (
"fmt"
"sync"
"sync/atomic"
"time"
"github.com/panjf2000/ants"
)
var sum int32
func myFunc(i interface{}) {
n := i.(int32)
atomic.AddInt32(&sum, n)
fmt.Printf("run with %d\n", n)
}
func demoFunc() {
time.Sleep(10 * time.Millisecond)
fmt.Println("Hello World!")
}
func main() {
defer ants.Release()
runTimes := 1000
// Use the common pool.
var wg sync.WaitGroup
syncCalculateSum := func() {
demoFunc()
wg.Done()
}
for i := 0; i < runTimes; i++ {
wg.Add(1)
ants.Submit(syncCalculateSum)
}
wg.Wait()
fmt.Printf("running goroutines: %d\n", ants.Running())
fmt.Printf("finish all tasks.\n")
// Use the pool with a function,
// set 10 to the capacity of goroutine pool and 1 second for expired duration.
p, _ := ants.NewPoolWithFunc(10, func(i interface{}) {
myFunc(i)
wg.Done()
})
defer p.Release()
// Submit tasks one by one.
for i := 0; i < runTimes; i++ {
wg.Add(1)
p.Invoke(int32(i))
}
wg.Wait()
fmt.Printf("running goroutines: %d\n", p.Running())
fmt.Printf("finish all tasks, result is %d\n", sum)
}
Integrate with http server
package main
import (
"io/ioutil"
"net/http"
"github.com/panjf2000/ants"
)
type Request struct {
Param []byte
Result chan []byte
}
func main() {
pool, _ := ants.NewPoolWithFunc(100, func(payload interface{}) {
request, ok := payload.(*Request)
if !ok {
return
}
reverseParam := func(s []byte) []byte {
for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
s[i], s[j] = s[j], s[i]
}
return s
}(request.Param)
request.Result <- reverseParam
})
defer pool.Release()
http.HandleFunc("/reverse", func(w http.ResponseWriter, r *http.Request) {
param, err := ioutil.ReadAll(r.Body)
if err != nil {
http.Error(w, "request error", http.StatusInternalServerError)
}
defer r.Body.Close()
request := &Request{Param: param, Result: make(chan []byte)}
// Throttle the requests traffic with ants pool. This process is asynchronous and
// you can receive a result from the channel defined outside.
if err := pool.Invoke(request); err != nil {
http.Error(w, "throttle limit error", http.StatusInternalServerError)
}
w.Write(<-request.Result)
})
http.ListenAndServe(":8080", nil)
}
Submit tasks
Tasks can be submitted by calling ants.Submit(func())
ants.Submit(func(){})
Customize limited pool
ants also supports customizing the capacity of pool. You can invoke the NewPool function to instantiate a pool with a given capacity, as following:
// Set 10000 the size of goroutine pool
p, _ := ants.NewPool(10000)
// Submit a task
p.Submit(func(){})
Tune pool capacity in runtime
You can tune the capacity of ants pool in runtime with Tune(int):
pool.Tune(1000) // Tune its capacity to 1000
pool.Tune(100000) // Tune its capacity to 100000
Don't worry about the synchronous problems in this case, the function here is thread-safe (or should be called goroutine-safe).
Release Pool
pool.Release()
About sequence
All tasks submitted to ants pool will not be guaranteed to be addressed in order, because those tasks scatter among a series of concurrent workers, thus those tasks would be executed concurrently.
Benchmarks
OS: macOS High Sierra
Processor: 2.7 GHz Intel Core i5
Memory: 8 GB 1867 MHz DDR3
Go Version: 1.9
-
BenchmarkGoroutine-4 represents the benchmarks with unlimited goroutines in golang.
-
BenchmarkPoolGroutine-4 represents the benchmarks with a
antspool.
The test data above is a basic benchmark and more detailed benchmarks are about to be uploaded later.
Benchmarks with Pool
In above benchmark picture, the first and second benchmarks performed test cases with 1M tasks and the rest of benchmarks performed test cases with 10M tasks, both in unlimited goroutines and ants pool, and the capacity of this ants goroutine-pool was limited to 50K.
As you can see, ants can up to 2x faster than goroutines without pool (10M tasks) and it only consumes half the memory comparing with goroutines without pool. (both 1M and 10M tasks)
Benchmarks with PoolWithFunc
Throughput (it is suitable for scenarios where asynchronous tasks are submitted despite of the final results)
100K tasks
1M tasks
10M tasks
Performance Summary
In conclusion, ants can up to 2x~6x faster than goroutines without a pool and the memory consumption is reduced by 10 to 20 times.
Documentation
¶
Index ¶
Constants ¶
const ( // DEFAULT_ANTS_POOL_SIZE is the default capacity for a default goroutine pool. DEFAULT_ANTS_POOL_SIZE = math.MaxInt32 // DEFAULT_CLEAN_INTERVAL_TIME is the interval time to clean up goroutines. DEFAULT_CLEAN_INTERVAL_TIME = 1 // CLOSED represents that the pool is closed. CLOSED = 1 )
Variables ¶
var ( // ErrInvalidPoolSize will be returned when setting a negative number as pool capacity. ErrInvalidPoolSize = errors.New("invalid size for pool") // ErrInvalidPoolExpiry will be returned when setting a negative number as the periodic duration to purge goroutines. ErrInvalidPoolExpiry = errors.New("invalid expiry for pool") // ErrPoolClosed will be returned when submitting task to a closed pool. ErrPoolClosed = errors.New("this pool has been closed") )
Functions ¶
Types ¶
type Pool ¶
type Pool struct {
// PanicHandler is used to handle panics from each worker goroutine.
// if nil, panics will be thrown out again from worker goroutines.
PanicHandler func(interface{})
// contains filtered or unexported fields
}
Pool accept the tasks from client,it limits the total of goroutines to a given number by recycling goroutines.
func NewTimingPool ¶
NewTimingPool generates an instance of ants pool with a custom timed task.
type PoolWithFunc ¶
type PoolWithFunc struct {
// PanicHandler is used to handle panics from each worker goroutine.
// if nil, panics will be thrown out again from worker goroutines.
PanicHandler func(interface{})
// contains filtered or unexported fields
}
PoolWithFunc accept the tasks from client,it limits the total of goroutines to a given number by recycling goroutines.
func NewPoolWithFunc ¶
func NewPoolWithFunc(size int, pf func(interface{})) (*PoolWithFunc, error)
NewPoolWithFunc generates an instance of ants pool with a specific function.
func NewTimingPoolWithFunc ¶
func NewTimingPoolWithFunc(size, expiry int, pf func(interface{})) (*PoolWithFunc, error)
NewTimingPoolWithFunc generates an instance of ants pool with a specific function and a custom timed task.
func (*PoolWithFunc) Free ¶
func (p *PoolWithFunc) Free() int
Free returns a available goroutines to work.
func (*PoolWithFunc) Invoke ¶
func (p *PoolWithFunc) Invoke(args interface{}) error
Invoke submits a task to pool.
func (*PoolWithFunc) Running ¶
func (p *PoolWithFunc) Running() int
Running returns the number of the currently running goroutines.
func (*PoolWithFunc) Tune ¶
func (p *PoolWithFunc) Tune(size int)
Tune change the capacity of this pool.
type Worker ¶
type Worker struct {
// contains filtered or unexported fields
}
Worker is the actual executor who runs the tasks, it starts a goroutine that accepts tasks and performs function calls.
type WorkerWithFunc ¶
type WorkerWithFunc struct {
// contains filtered or unexported fields
}
WorkerWithFunc is the actual executor who runs the tasks, it starts a goroutine that accepts tasks and performs function calls.
Source Files
Directories